JP2000163087A - Circuit for preventing leading edge part of telephone signal from missing in communication equipment using voice switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a leading part of a telephone signal from missing due to a delay in switching operation for changing over voices in a communication equipment changing over transmission to/from reception by the presence or absence of voice. SOLUTION: In a communication equipment using a voice switch, it is possible to prevent a leading part of voice from missing by A/D-converting a voice signal from a microphone 11, storing the data in a memory circuit once for a certain period of time and then reading it from the memory circuit again to D/A-converting it into the original signal, and on the other hand changing over the voice switch to/from transmission from/to reception when an output of the A/D converter is compared with a reference value for a certain period of time shorter than a read delay time of the memory circuit and the output continues to be larger than the reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for preventing loss of a rising portion of a transmission signal of a communication device using a voice switch.

[0002]

2. Description of the Related Art Conventionally, a communication device using a voice switch includes a microphone 51 and a voice detection circuit 52 which rectifies a voice signal from the microphone and determines that an input signal is present when the voice signal exceeds a certain level, as shown in FIG. It is composed of a voice control circuit 53 controlled by a voice detection circuit.

An audio signal is converted into an electric signal by a microphone 51, and when it is judged by a sound detection circuit 52 that a signal has been input, an audio control circuit 53 is switched to be sent to a communication partner.

[0004]

By the way, in the conventional circuit, even if a voice signal is input, a time delay occurs in which the voice detection circuit 52 detects the voice. The quality was significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned difficulties, and has as its object to prevent the beginning portion of a transmission signal from being lost even if a time delay for voice detection occurs. I do.

[0006]

In order to achieve the above object, a circuit for preventing a rising portion of a transmission signal of a communication apparatus using a voice switch according to the present invention detects a microphone and the presence or absence of a voice signal. It is composed of a voice detection circuit, a voice delay circuit, and a voice control circuit controlled by the voice detection circuit. The voice delay circuit converts an analog signal from the handset into a digital signal and a digital signal transmitted from the AD converter. A data memory for storing data for a fixed time, a DA converter for converting digital data sent from the data memory into an original analog signal, and a memory control circuit for sending the data stored in the data memory to the DA converter after a certain time; It consists of.

Here, the operation when the voice switch is switched will be described. The signal comparison circuit compares the output of the AD converter with the initially set data, outputs a pulse signal when the output of the AD converter is large, counts the pulse signal for a certain gate time, and exceeds a certain number of pulses. If so, the voice detection circuit determines that a voice input has been made and switches from the receiving state to the transmitting state. However, there is a delay corresponding to the time for counting the pulse signal for a certain gate time.
Even if this delay occurs, the signal is transmitted to the voice control circuit with a delay by the voice delay circuit, so even if there is a delay in the voice detection circuit, the first part of the transmission signal is not lost to the other party to talk. A transmission signal is sent.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a circuit for preventing loss of a rising part of a transmission signal of a communication device using a voice switch according to the present invention.

The configuration of a communication device according to the present invention will be described with reference to FIG. A circuit for preventing a loss of a rising portion of a transmission signal of a communication device using a voice switch includes a microphone 11, a voice delay circuit 13 that outputs a voice signal from the microphone after a predetermined time, and an A / D converter 13 a in the voice delay circuit. A signal comparing circuit 12a for judging the presence or absence of a sound using a signal and a sound control circuit 14 controlled by the sound detecting circuit 12 are provided. A sound delay circuit 13 converts an analog signal from the microphone into a digital signal. 13a and a data memory 13b for storing digital data sent from the AD converter for a certain period of time, and a DA converter 1 for converting the digital data sent from the data memory into an original analog signal.
3d and a memory control circuit 13c for sending the data stored in the data memory to the DA converter after a predetermined time.

The operation of the present invention will be described with reference to FIG. The audio signal f1 shown in FIG. 2A converted into an electric signal by the microphone 11 is sent to the AD converter 13a,
The digital signal is converted into a digital signal at a, and the required amount of delay time is sequentially stored in the data memory 13b.
3a simultaneously sends a signal serving as a reference for the delay time to the memory control circuit 13c. Next, the memory control circuit 13c of the audio delay circuit performs a certain time t1 based on the signal serving as the reference of the delay time.
The data in the data memory 13b is controlled to be delayed and sent to the D / A converter 13d, and the sent digital signal is converted into the original analog signal by the D / A converter 13d, and the sound is delayed for a certain time t1 as shown in FIG. The signal is sent to the control circuit 14 and transmitted to the other party on the call. In this case, the fixed time t1 to be delayed is, of course, extremely short so as not to hinder the communication and is longer than the delay time of the voice detection circuit.

Now, consider the timing at which the voice detection circuit detects and switches voice. When the audio signal from the microphone 11 is sent to the audio delay circuit 13, it is converted into a digital signal by the AD converter 13a and sent to the signal comparison circuit 12a. Here, if the input level is higher than the set value, the signal comparison circuit generates the pulse shown in FIG.

The pulse signal is counted for a certain gate time, and when the number of pulses becomes equal to or more than a certain number of pulses, transmission and reception are switched as shown in FIG. In this case, a delay of time t2 corresponding to the gate time occurs. On the other hand, since the audio signal is transmitted to the audio control circuit 14 with a delay of the time t1 by the audio delay circuit, if the time t1 is made longer than the time t2, the signal shown in FIG.
As described above, it is possible to prevent the loss of the rising part of the transmission signal.

[0013]

As is apparent from the above description, according to the present invention, it is possible to prevent a loss of a rising portion of a transmission signal of a communication device using a voice switch, thereby improving a communication quality. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a circuit for preventing a loss of a rising portion of a transmission signal of a communication device using a voice switch of the present invention.

FIG. 2 is a timing chart illustrating the operation of the present invention.

FIG. 3 is a configuration diagram illustrating a configuration of a conventional communication device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Communication equipment 11 ... Microphone 12a ... Signal comparison circuit 12 ... Voice detection circuit 13 ... Voice delay circuit 13a ... AD converter 13b ... Data memory 13c ... Memory control circuit 13d ... DA converter 14 ... Voice control circuit

Claims (1)

[Claims] 1. A microphone (11), an audio delay circuit (13) for outputting an audio signal from the microphone after a predetermined time, and an audio control circuit (14), wherein the audio delay circuit converts an analog signal from the microphone. A to convert to digital signal
A data memory (1) for accumulating digital data sent from the D converter (13a) and the AD converter for a predetermined time;
3b) and a DA converter (13d) for converting digital data sent from the data memory into an original analog signal
And a memory control circuit (13c) for sending the data stored in the data memory to the DA converter after a predetermined time, wherein the voice control circuit compares the output of the AD converter with a certain reference value, and And a voice detection circuit (12a) for detecting the presence or absence of voice based on the number of pulse inputs from the signal comparison circuit within a fixed gate time. A circuit that prevents a loss of a rising part of a transmission signal of a communication device that uses a voice switch.